After running Bandicam and proceeding to play a game, I received a steam message. I could not see the message pop-up, and the reminder of Shift+Tab overlay toggle did not appear. I tried pressing Shift+Tab, and it did not toggle the overlay. I set the toggle binding to various other keystrokes, but it still didn't work.

When I do not run Bandicam, I'm able to toggle Steam overlay and see pop-ups.